Study On Degradation And Rapid Determination Methods Of Trace Organosphosphorus Pesticides

Production and application of organophosphorus pesticides as main species in pesticide market of our country are time-honored.Organophosphorus pesticides play an important role in the respects of crop protection and control of indoor parasites.While organophosphorus pesticides bring agriculture foison,more attention is paid to the problems of food security caused by pesticides,because of faced stress and threats from ecological environment and human health. Degradation or removal methods of organophosphorus pesticides consist of physical degradation,catalyzed oxidative degradation,irradiated degradation by light and biological degradation.Determination methods of organophosphorus pesticides involves mainly spectrometry,chromatography and enzymatic method.Two parts are included in this paper.In the first part,oxidative degradation of dichlorvos catalyzed by metalloporphyrins were reported,while oxidants were sodium persulfate,hydrogen peroxide,peracetic acid and sodium hypochlorite, respectlivey.Influence of different metalloporphyrins and oxidants on the ratio of degradation were discussed.Finally,degradation effect of dichlorvos by using mixed oxidants of sodium persulfate and hydrogen peroxide catalyzed by cobalt tetrakis(4-sulfonatophenyl)porphyrin (CoTPPS₄) were researched.As a result,the catalytic effect of metalloporphyrins on degradation reaction of pesticides were founded, catalytic activity of CoTPPS4 among all metalloporphyrins was very high and degradation ratio of dichlorvos rised to maximun when volume ratio of mixed oxidants of sodium persulfate and hydrogen peroxide was 4:1.Two novel,rapid,simple and sensitive methods for determination of acephate,omethoate,phorate of organophosphorus pesticides were developed in the second part, based on metal ions of Pd(II) and Ag(I) enable capable of forming complexes with organophosphorus pesticides or hydrolysates of them.Absorption of the complex compounds increase firstly and then decrease as more and more volume of acids and metal ions were added.The optimal addition of various reagents were selected as a result of orthogonal tests,detection limits and molar absorptivity at maximun wavelength of methods developed were detected,the magnitude order of molar absorptivity reached 10⁵.